On 07/29/2015 06:21 PM, Eric W. Biederman wrote:
Two quick questions.
- What motivates this work? Are you seeing lots of
parallel reads on proc?
The micro-benchmark that I used was artificial, but it was used to
reproduce an exit hanging problem that I saw in real application. In
fact, only allow one task to do a lookup seems too limiting to me.
- Why not rcu? Additions and removal of proc generic
files is very rare. Conversion to rcu for reads should
perform better and not take much more work.
RCU is harder to verify its correctness, whereas rwlock is easier to use
and understand. If it is really a performance critical path where every
extra bit of performance counts, I will certainly think RCU may be the
right choice. However, in this particular case, I don't think using RCU
will give any noticeable performance gain compared with a rwlock.
Cheers,
Longman
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